PROJECT SUMMARY According to World Health Organization, approximately 1.5 billion people, or 24% of the world?s population, are infected with helminths worldwide. Heavily infected people, particularly children, are nutritionally and physically impaired. Due to rapid reinfection, limited efficacy of current drugs, and a lack of effective vaccines, the eradication of helminth infections remains challenging. There is an urgent need for new preventive medicines and effective anthelminthic drugs. Recent evidence indicates that intestinal epithelial tuft cells can be a direct target and sensor of helminth. Tuft cell-derived interleukin-25 (IL-25) induces type 2 innate lymphoid cells (ILC2s) and CD4+ T helper 2 (Th2) cells, which secrete type 2 cytokines such as IL-13 and IL-4 to drive the differentiation and hyperplasia of epithelial tuft and goblet cells. This feedforward response comprised of tuft cells, ILC2, and epithelial progenitors is responsible for the ?weep and sweep? of parasitic worms. Although the regulatory circuit associated with type 2 immunity is beginning to be established, little has been elucidated regarding the molecular mechanisms underlying the epithelial remodeling. The research in my laboratory has been focused on the pathophysiological role of O-linked N-Acetylglucosamine (O-GlcNAc) modification, which modifies intracellular proteins at serine and threonine residues. The long-term goal of our research is to understand how protein O- GlcNAcylation orchestrates mucosal responses to pathogens like parasitic helminths. In the proposed study, we will test the hypothesis that protein O-GlcNAcylation, by modifying STAT6, is indispensable for tuft cell-initiated intestinal epithelial remodeling and type 2 immune responses to helminth infections. In Aim 1, we hypothesize that OGT promotes the differentiation of tuft and goblet cells from epithelial progenitors, via STAT6 O- GlcNAcylation. By mapping STAT6 O-GlcNAcylation sites and analyzing functions in organoid cultures, we will determine the cellular and molecular mechanisms by which O-GlcNAcylation controls tuft cell development. In Aim 2, we will use pharmacological and genetic approaches to increase global protein O-GlcNAcylation in the mouse intestine, and test whether the augmentation of intestinal O-GlcNAcylation levels boosts epithelial remodeling and type 2 immune responses to expulse helminths. The proposed study will provide valuable insights into the development of new intervention strategies to eradicate parasitic worms in areas of poverty in the developing world and to treat allergic and autoimmune diseases in industrialized countries.